Tag Archives: Hurricanes

The 2018 extended range tropical forecast has been released updated by Colorado State University Department of Atmospheric Science.

As at April 5 July 2, the forecast is for slightly above average storm activity below average activity for the Atlantic Ocean basin. The current weak La Niña is not expected to transition into a significant El Niño by summer and fall. El Niño conditions create vertical wind shear that inhibits hurricane formation. Without wind shear, the tropical Atlantic is conducive to storm development.

We have decreased our forecast and now believe that 2018 will have below-average activity. The tropical and subtropical Atlantic is currently much colder than normal, and the odds of a weak El Niño developing in the next several months have increased. With the decrease in our forecast, the probability for major hurricanes making landfall along the United States coastline and in the Caribbean has decreased as well.

Broad swath of property damage, trees downed, and power outages across Florida from Irma

Minor damage to Anna Maria Island properties and trees. Maximum wind reported was 92mph as the eye of Irma traveled inland of the island

Anna Maria City Pier and restaurant damaged beyond repair

Anna Maria City Pier hurricane damage Photo: Jack Elka, The Islander

Some Ficus, Banyan, Norfolk Pines blew over

The 2017 hurricane season was more active than predicted by the Colorado State University Tropical Meteorology Project forecast team. Three major hurricanes struck the United States: Harvey, Irma and Maria, causing devastating destruction to islands in the Caribbean and other portions of the tropical Atlantic:

“The 2017 hurricane season was extremely active. Overall, our predicted numbers from our early July and August issue dates for named storm and hurricane formations were relatively close to what was observed, but our early season predictions and our predictions for integrated metrics such as Accumulated Cyclone Energy (ACE) were far too low,” said Phil Klotzbach, lead author of the forecast at CSU.

The season’s first updated June forecast for Atlantic hurricanes in 2017 has been released by the Colorado State University Tropical Meteorology Project.

(April 6 ) This year, 2017, the expectation is for a “below average” year, based on 29 years of observations from 1981 to 2010. There is the potential for shear-enhancing El Niño conditions to develop over the next several months. The tropical Atlantic has cooled over the past month, and the far North Atlantic is currently colder than normal. These cold anomalies tend to force atmospheric conditions that are less conducive for Atlantic hurricane formation and intensification.

(June 1) We have increased our forecast and now believe that 2017 will have approximately average activity. The odds of a significant El Niño in 2017 have diminished somewhat, and portions of the tropical Atlantic have anomalously warmed over the past two months. While the tropical Atlantic is warmer than normal, the far North Atlantic remains colder than normal, potentially indicative of a negative phase of the Atlantic Multi-Decadal Oscillation. We anticipate a near-average probability for major hurricanes making landfall along the United States coastline and in the Caribbean.

We anticipate that the 2017 Atlantic basin hurricane season will have slightly below- average activity. The current neutral ENSO is likely to transition to either weak or moderate El Niño conditions by the peak of the Atlantic hurricane season. The tropical Atlantic has anomalously cooled over the past month and the far North Atlantic is relatively cold, potentially indicative of a negative phase of the Atlantic Multi-Decadal Oscillation. We anticipate a below-average probability for major hurricanes making landfall along the United States coastline and in the Caribbean. As is the case with all hurricane seasons, coastal residents are reminded that it only takes one hurricane making landfall to make it an active season for them. They should prepare the same for every season, regardless of how much activity is predicted. by Philip J. Klotzbach and Michael M. Bell (as of 6 April 2017)

An analysis of a variety of different atmosphere and ocean measurements (through March) which are known to have long-period statistical relationships with the upcoming season’s Atlantic tropical cyclone activity indicate that 2017 should have slightly below-average activity. The big question marks with this season’s predictions are whether an El Niño develops, as well as what the configuration of Sea Surface Temperatures will look like in the tropical and far North Atlantic Ocean during the peak of the Atlantic hurricane season.

June 1 – Our confidence that a weak to moderate El Niño will develop has diminished since early April. While upper ocean content heat anomalies have slowly increased over the past several months, the transition towards warm ENSO conditions appears to have been delayed compared with earlier expectations. At this point, we believe that the most realistic scenario for the 2017 Atlantic hurricane season is borderline warm neutral ENSO to weak El Niño conditions. There remains a need to closely monitor ENSO conditions over the next few months. Additional discussion of ENSO will be included with the July 1 and August 4 updates.

2017 Forecast numbers:

Atlantic Hurricane Season

April June 2017 forecast

29-year Median

Named storms (>35mph winds)

11 13

12

Hurricanes (>72mph winds)

4 6

6.5

Major hurricanes (>111mph winds)

2 2

2

US landfall likelihood

42% 55%

52%

Gulf Coast landfall probability

24% 32%

30%

Major Hurricane in Caribbean
probability

34% 44%

42%

Manatee County hurricane landfall
probability*

0.6% 0.7%

0.7%

Manatee County tropical storm
probability*

14.7% 18.3%

17.1%

Manatee County >75mph wind gusts
probability*

4.2% 5.4%

5.0%

*

Tracks of major hurricanes making Florida peninsula and East Coast landfall during 1916-1965 and1966-2015.

On August 18th, a weather disturbance in the Atlantic Ocean formed into an area of tropical interest and labelled “Invest 99L” by meteorologists. For ten days it crept across the ocean and meandered in the eastern Caribbean. By Monday August 29th, Tropical Depression 9 hatched, and unconstrained by prior nearby steering winds headed into the Gulf of Mexico to become Tropical Storm Hermine on Wednesday.

West Florida went on high alert. Storms this close sometimes run up the coast like Tropical Storm Debby (2012), sometimes change direction suddenly or quickly intensify like Hurricane Charley (2004). In any case Hermine looked like it would be a rain-maker like Tropical Storm Colin earlier this year.

Combined with 2½ feet of surge on top of 2½ foot high tides, torrential and long-lasting rainfall overwhelmed the newly installed “percolation” pit drainage, causing what many people described as the worst flooding they have ever seen on the island. Schools closed Thursday, roads became impassable, and sewers backed up. Power stayed on apart from a short outage when a falling tree brought down some lines.